For the first time ever, King County plans to close its offices for 10 days next year because it doesn’t have enough money to pay the bills and maintain basic services.

The shutdown of all “nonessential services,” announced by County Executive Ron Sims Monday, would not affect sheriff’s patrols, jail operations, Metro transit service or wastewater treatment. The closures would be spread throughout the year, with the first scheduled for Jan. 2.

Sims said he was confident that members of 15 county-employee unions would ratify the deal, under which workers would not be paid for the 10-day furlough. If employees don’t agree, Sims said he would, “without question,” order them to take the time off.

“I’m proud of my relationship with the labor unions and commend their leadership for wanting to be part of the solution during these difficult times,” Sims said after the tentative agreement was reached Monday morning with the King County Coalition of Unions.

The furlough — which would apply to nonunion workers along with about 7,000 union employees — is expected to save the county $15 million and prevent deeper program cuts in the face of a $93 million general-fund shortfall.

Sims announced this month he planned to reduce a scheduled cost-of-living adjustment (COLA) for nonunion employees and said he would ask the unions for comparable wage concessions. But the unions balked at reducing COLAs, and the focus of negotiations shifted to the 10-day furlough, officials in Sims’ office and the labor coalition said.

Dustin Frederick, co-chairman of the Coalition of Unions, said he wasn’t sure whether the rank and file would approve the deal in a series of votes set to conclude by Nov. 17.

He said the unions are asking attorneys whether Sims can order union members to go on furlough without their consent.

“Labor can either vote for the tentative agreement, which makes the best out of a bad situation, or they can play poker and vote it down and see if the executive imposes it, which he says he’s going to,” Frederick said.

The planned furlough would effectively reduce employees’ cost-of-living increases from a scheduled 4.9 percent to 1 percent next year. Labor leaders told members that without the furlough, 120 more union workers would lose their jobs in addition to the 126 employees who have already received layoff notices.

Five of the Metropolitan King County Council’s nine members issued a statement praising labor representatives for agreeing to the furlough, and saying the council would close its doors to save the county another $450,000.

Councilmembers Julia Patterson, Reagan Dunn, Larry Phillips, Kathy Lambert and Bob Ferguson also said they would return to the county the portion of their cost-of-living increases above 1 percent. They made that statement shortly after Sims said he wouldn’t take a cut in his COLA because he isn’t legally allowed to.

Sims said he hadn’t sought any pay concessions from Metro bus drivers, sheriff’s deputies or jail guards because those workers couldn’t be furloughed without jeopardizing public safety and transportation.

While the furloughs will result in limiting thousands of employees’ pay increases to 1 percent, sheriff’s deputies will receive a base pay increase of 5 percent next year if the County Council approves a five-year contract that deputies ratified Friday. Most deputies will also get pay premiums of 4 to 10 percent for special duties or educational achievement.

King County Police Officers’ Guild attorney and negotiator Chris Vick said the 97 percent yes vote for the contract was unusually lopsided. He said higher pay was, in part, a trade-off for accepting more civilian oversight and giving the sheriff more disciplinary authority.

“They say timing is everything,” he said. “There’s nothing like the country going into a recession to make people think twice about wanting to hold out for more. I think it’s a good contract and it brings in civilian review in a way that I think officers are going to view it as fair and not turning the circus over to the clowns.”